Shark Surprises Aquarium With Rare ‘Virgin Birth’

For the first time, scientists have recorded a shark switching from sexual to asexual reproduction.

WATCH: Leonie, a female zebra shark, is the first shark to reproduce through parthenogenesis after previously giving birth through sexual reproduction. Select photos courtesy Tourism and Events Queensland

Shark Surprises Aquarium With Rare ‘Virgin Birth’

For the first time, scientists have recorded a shark switching from sexual to asexual reproduction.

WATCH: Leonie, a female zebra shark, is the first shark to reproduce through parthenogenesis after previously giving birth through sexual reproduction. Select photos courtesy Tourism and Events Queensland

Scientists in Australia published a paper on Tuesday about a female shark that performed a “virgin birth.” Although she hadn’t been around a male shark in three years, the captive zebra shark—named Leonie—laid eggs that hatched three viable pups. (Read our earlier story about the birth.)

Leonie had previously given birth after mating with a male shark at the Reef HQ aquarium in Townsville, Queensland. In 2012, she was moved into a separate tank at the aquarium with no male sharks.

In her new tank, Leonie continued to lay eggs whether they were fertilized or not, just like chickens do. Yet after three years of separation from a male, scientists were stunned to see some of her eggs hatch.

Although this switch from sexual reproduction to parthenogenesis—reproduction without fertilization—is a first for sharks, it has also been observed in a spotted eagle ray and a Colombian rainbow boa.

In the snake’s case, her offspring couldn’t have been fertilized by sperm, because she had never been near a male. Yet Leonie had. And so when the zebra shark gave birth, scientists at the Queensland aquarium also wondered if stored sperm was to blame. Further tests, however, revealed that the pups’ lack of genetic diversity meant they were most likely the spawn of one parent, not two.

Two of Leonie’s pups—Cleo and CC—swim around at the Reef HQ aquarium in Townsville, Queensland, Australia. Genetic tests confirm they were the spawn of one parent, not two.

Photograph courtesy Tourism and Events Queensland

“We think it happens because females become isolated from males,” he says.

Whether the resulting offspring are fertile “is one of the interesting questions about all of this,” he says. “One study did find that a shark produced via parthenogenesis went on to give birth asexually.”

Having offspring with less genetic diversity isn’t ideal, but Feldheim thinks it might be a last-ditch effort for the female to reproduce.

“If a female colonizes an island, for example, or an area where males are rare or absent, parthenogenesis is a way for her to still pass on her genes,” he says.

Although scientists don’t know how common parthenogenesis is among species that normally reproduce through fertilization, Feldheim says that it does not occur among mammals.